In a heavy non-aluminum pan, bring the mustard seeds to a boil in the cold water. Simmer for 5 minutes to remove bitterness; then strain, discarding water. Lightly rinse the mustard seeds with cold water.
Put the strained and rinsed mustard seeds in a food processor. Add shallot, garlic, parsley, peppercorns, dried juniper berries, marjoram, tarragon, olive oil, and balsamic vinegar; puree until smooth. If the mixture is too thick, add additional olive oil. Season to taste with salt.
Serve at room temperature.
Yields approximately 3 cups.
* The dried berries should be crushed well just before using as the flavor will decline rapidly once exposed to the air. You wil not need many juniper berries, three or four of the berries will flavor most dishes without overpowering the main ingredient or other seasonings. Learn more about using Juniper Berries in your cooking.
Juniper Berry Vinaigrette Recipe: https://whatscookingamerica.net/Salad/JuniperBerryVinaigrette.htm